Grease an 11 x 17 inch glass baking dish with vegetable oil. Line the dish with lightweight aluminum foil and lightly coat the foil with more oil.
In the bowl of a standing electric mixer, soften the gelatin with ¾ cup of the water.
Place the sugar, corn syrup, remaining ¾ cup water and the sea salt in a heavy saucepan. Bring to a boil and cook over high heat until the syrup reaches 234 to 240 degrees Fahrenheit, or the soft-ball stage on a candy thermometer.
With the whisk attachment of the mixer at full speed, beat the hot syrup slowly into the gelatin until mixture is very stiff, about 15 minutes. Beat in the vanilla. Pour the mixture into the foil-lined dish and smooth the top with an oiled spatula.
Sprinkle the top with s.a.l.t. sisters naturally flavored raw cane sugar(s). For added variety, you can sprinkle part of the mixture with one flavor, and part with another flavor.
Allow the mixture to rest, uncovered, at room temperature 10-12 hours.
Using a fine sieve, sprinkle the confectioners’ sugar onto a cutting board. Turn the stiffened marshmallow mixture out onto the sugar and, using a small, lightly oiled knife or square cutter, cut into squares. Be sure to dip the cut edges of the marshmallows into confectioners’ sugar to prevent sticking.
Keep in an airtight container. Best when eaten within two days of being made.
Try using these marshmallows in your hot cocoa. For a grown-up flavor, create a “sweet heat” treat by choosing Habanero naturally-flavored cane sugar in hot cocoa.